Outflow regulator for a gravity-fed liquid outlet

An outflow regulator for a gravity-fed liquid outlet of a liquid reservoir, the liquid outlet being located in the reservoir so as to be crossed by a liquid effluent flowing in a generally horizontal direction from an upstream side of the outlet to a downstream side, the outflow regulator comprising:

• a restriction plate mountable within the liquid outlet for limiting a flow rate of the effluent, the restriction device comprising:
• a lower orifice allowing a first passage for the effluent when a first predetermined level of liquid is reached within the liquid reservoir;
• and
• an upper orifice located above the first orifice and allowing a second passage for the effluent when a second predetermined level of liquid is reached within the reservoir;
• and
• a closure device comprising:
• a flapgate on the downstream side of the restriction plate, the flapgate being pivotable between a closed position where the flapgate covers the lower orifice of the restriction device and an opened position away from the restriction device, the flapgate including an opening facing the upper orifice of the restriction plate when the flapgate is in the closed position;
• whereby the flapgate, in the closed position, closes the first passage and leaves the second passage free;
• and
• a float counterweight operatively connected to the flapgate to urge the flapgate towards the opened position when the liquid level in the reservoir is lower than said second predetermined level and causing the flapgate to move to the closed position when the liquid level in the reservoir reaches the second predetermined level.